University of Khartoum

Survay and Molecular Characterization of Xanthomonas Vesicatoria Causing Bacterial Spot of Tomato in Blue Nile State

Survay and Molecular Characterization of Xanthomonas Vesicatoria Causing Bacterial Spot of Tomato in Blue Nile State

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Title: Survay and Molecular Characterization of Xanthomonas Vesicatoria Causing Bacterial Spot of Tomato in Blue Nile State
Author: Mohammed, Fatima Elfatih Idreis
Abstract: Bacterial spot disease of tomato caused by Xanthomonas vesicatoria is a major constraint to tomato production in Sudan leading to significant crop losses. This study aimed to survey, characterize, and Identify the causal pathogen of tomato bacterial spot (TBS). The survey evaluated the disease incidence and severity on tomato cultivated in Blue Nile State during the Autumn season. The surveyed sites were in AL-rossires and AL-damazein localities. Four farms were selected from each locality. Symptomatic leaves were collected and sent to plant pathology laboratory, Department of Crop protection, faculty of Agriculture University of Khartoum for isolation and identification the pathogen. Pathogenicity of the isolated bacterium was confirmed by pathogenicity test. Then the bacterium was characterized, morphologically, biochemically and at molecular level. The survey revealed that there was no significant differences in disease incidence within each locality, while they was significant difference (P ≤ 0.05) between localities in disease severity was obtained. The percentage of disease incidence in ALrosires locality Alrosires, Tiba,Bdoos and ALgrif was 52.17, 51.55 , 46.92 46.45%, while the severity was 35.25, 29.20, 26.75 and 21.92% respectively. On the other hand, disease incidence at ALdmazein locality AL-regiba, ALseriow, Abormad and Haroon was 56.40, 56.86, 55.00 and 45.42%, and the severity was 18.91, 34.93, 32.35 and 33.10%, respectively. The results showed that the isolates were rod shaped, obligate aerobic, gram negative, catalase positive, oxidase negative, starch and gelatein hydrolysis and yellow colonies on nutrient agar medium and Yeast Dextrose Calcium carbonate (YDC) medium. From the pathogenicity test, the isolates showed pathogenic reaction on tomato plants. Accordingly, the bacterium was identified as Xathanthomonas vesicatoria. The identity of the bacterium was confirmed by PCR and sequence analysis of the 16S RNA gene. With PCR amplification, the bacterium isolated from the infected tomato plants produced 1500 bp amplicon. Similarity among the isolates reached 97%. These results also indicate that the tomato plants grown in Blue Nile State were highly infected by the bacterial leaves spot,more investigations must carried out in management of tomato plant in Sudan.
URI: http://khartoumspace.uofk.edu/123456789/27061


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